Tiny black bugs

I found these "very tiny" black bugs on my bathroom floor. At first I just thought it was a speck of dirt, but they crawl. I haven't noticed if they jump or not. Can't really describe them because they are sooo small. I've only seen them on the floor. It has been very hot and dry where I live. I have a bathroom window that has been up constantly because of the heat. Any ideas? Are they harmful? Can I get rid of them? They gross me out!